Pneumatic actuator, pressure wave generator, and method for operating a pressure wave generator

Abstract

A pneumatic actuator (4b), in particular for use in a pressure wave generator (1) comprises: a first piston surface (91) which acts counter to a gaseous working medium in a first volume (41), wherein a pressure in the first volume (41) effects an actuator force in a first direction upon the first piston surface (91); a second piston surface (92) which acts counter to the working medium in a second volume (42), wherein a pressure in the second volume (42) effects an actuator force in a second direction opposite to the first direction, upon the second piston surface (92); a throttle between the first volume (41) and the second volume (42); an inlet/outlet opening (45) of the first volume (41) for bringing the working medium into and discharging it out of, the first volume; wherein the first piston surface (91) is larger than the second piston surface (92).

Claims

1. A pneumatic actuator (4b), comprising a first piston surface (91) which acts counter to a gaseous working medium in a first volume (41), wherein a pressure in the first volume (41) effects an actuator force in a first direction upon the first piston surface (91); a second piston surface (92) which acts counter to the working medium in a second volume (42), wherein a pressure in the second volume (42) effects an actuator force in a second direction which is opposite to the first direction, upon the second piston surface (92); a throttle between the first volume (41) and the second volume (42); an inlet/outlet opening (45) of the first volume (41) for bringing the working medium into and discharging it out of the first volume (41); wherein the first piston surface (91) is larger than the second piston surface (92).

2. The pneumatic actuator (4b) according to claim 1, comprising an end position damping for closing the inlet/outlet opening (45).

3. The pneumatic actuator (4b) according to claim 1, wherein a piston closure element (95) is arranged for closing the inlet/outlet opening (45).

4. The pneumatic actuator (4b) according to claim 3, wherein the piston closure element (95) is also arranged for separating a working medium filling conduit (48: 101) with respect to the first volume (41).

5. The pneumatic actuator (4b) according to claim 1, wherein the first piston surface (9) and the second piston surface (92) are formed on the same piston (93).

6. The pneumatic actuator (4b) according to claim 1, wherein the first piston surface (91) and the second piston surface (92) are formed on separate pistons (93), whose movements are mechanically coupled to one another.

7. The pneumatic actuator (4b) according to claim 1, wherein the first piston surface (91) and a piston closure element (95) for closing the inlet/outlet opening (45) are formed on the same piston (93).

8. The pneumatic actuator (4b) according to claim 1, comprising a cylinder discharge valve (46) for the rapid discharge of the working medium out of the first volume (41) by way of opening the inlet/outlet opening, wherein the cylinder discharge valve (46) comprises a piston surface (52), on which a force for closing the cylinder discharge valve (46) arises on subjection to the working medium, and a valve surface (53) on which a force in the opening direction of the cylinder discharge valve (46) arises on subjection to the working medium, and wherein the valve surface (53) is smaller than the piston surface (52).

9. The pneumatic actuator (4b) according to claim 8, comprising a discharge pilot valve (47) for discharging working medium out of a discharge valve volume (51) in which the working medium acts upon the piston surface (52).

10. The pneumatic actuator (4b) according to claim 8, wherein a working medium filling conduit (48) is arranged for filling the discharge valve volume (51) as well as the first volume (41) with working medium at the same pressure.

11. The pneumatic actuator (4b) according to claim 10, wherein a section (101) of the working medium filling conduit (48), through which section the first volume (41) is supplied with working medium, runs through the cylinder discharge valve (46), in particular through a shut-off body of the valve.

12. The pneumatic actuator (4b) according to claim 1, wherein a linear guidance of the piston (93) is formed by way of the piston (93) encompassing a rear closure guide (98) and being linearly movable in a movement direction along the rear closure guide, and a hollow-cylindrical piston connection element (94) which extends in the movement direction away from the piston (93) encompassing a bearing element (14) which is fastened to the rear closure guide (98) and wherein the second volume (42) is formed between the piston (93), an inner side of the piston connection element (94), the bearing element (14) and the rear closure guide (98).

13. A pressure wave generator (1), with a main explosion chamber (2), a closure element (9) which in a closure position closes the main explosion chamber (2) with respect to the outlet and in an opening position permits a flow of explosion gases out of the main explosion chamber (2) into the outlet, and an ignition means for igniting an explosion in the main explosion chamber (2), characterised in that the pressure wave generator (1) comprises a pneumatic actuator according to claim 1, and the closure element (9) can be brought from the closure position into the open position and in particular can also be brought from the opening position into the closure position, by way of the pneumatic actuator (4b).

14. The pressure wave generator (1) according to claim 13, wherein the pressure wave generator (1) comprises a control (20) which is designed to activate an opening movement of the closure element (9) when a pressure in the main explosion chamber (2) exceeds a predefined threshold value.

15. The pressure wave generator (1) according to claim 14, wherein the ignition means is an ignition means which can be constantly supplied with energy, in particular a glow plug (5b).

16. The pressure wave generator (1) according to claim 13, wherein the pressure wave generator (1) comprises a control (20) which is designed to activate an opening movement of the closure element (9) and after the completion of a settable ignition delay time after the activating of the opening movement, to ignite the explosion in the main explosion chamber (2).

17. The pressure wave generator (1) according to claim 16, wherein the ignitions means is a spark-generating ignition means, in particular a spark plug (5).

18. A method for operating a pneumatic actuator (4b) which comprises: a first piston surface (91) which acts counter to a gaseous working medium in a first volume (41), wherein a pressure in the first volume (41) effects an actuator force in the first direction upon the first piston surface (91); a second piston surface (92) which acts counter to the working medium in a second volume (42), wherein a pressure in the second volume (42) effects an actuator force in a second direction which is opposite to the first direction, upon the second piston surface (92); with the following steps: filling the first volume (41) with a gaseous working medium which is under pressure, in particular by way of a filling valve, for example a pressurised air valve (49); pressure compensation between the first volume (41) and the second volume (42) through a throttle and, by way of this, on account of a surface area difference between the first piston surface (91) and the second piston surface (92), moving the actuator in the first direction; discharging at least a part of the working medium out of the first volume (41), in particular by way of opening an inlet/outlet opening of the first volume (41); by way of a more rapid pressure drop in the first volume (41) than in the second volume (42), moving the actuator in the second direction.

19. A method for operating a pressure wave generator (1) with a main explosion chamber (2), amid the use of a pneumatic actuator (4b), which comprises: a first piston surface (91) which acts counter to a gaseous working medium in a first volume (41), wherein a pressure in the first volume (41) effects an actuator force in a first direction upon the first piston surface (91); a second piston surface (92) which acts counter to the working medium in a second volume (42), wherein a pressure in the second volume (41) effects an actuator force in a second direction which is opposite to the first direction, upon the second piston surface (92); comprising the repeated execution of the following steps: filling the first volume (41) with a gaseous working medium which is under pressure, in particular by way of a filling valve, for example a pressurised air valve (49); pressure compensation between the first volume (41) and the second volume (42) through a throttle and by way of this, on account of the surface area difference of the first piston surface (91) and the second piston surface (92), moving the actuator in the first direction and by way of this moving the closure element (9) in a closure direction and closing the main explosion chamber (2); filling the main explosion chamber (2) with an explosive mixture; igniting an explosion in the main explosion chamber (2), and discharging at least a part of the working medium out of the first volume (41), in particular by way of opening an inlet/outlet opening of the first volume (41), and by way of this opening the main explosion chamber (2); by way of a more rapid pressure drop in the first volume (41) than in the second volume (42), moving the actuator in the second direction and, by way of this, moving a closure element in the opening direction for opening the main explosion chamber (2) with respect to an outlet (15), and discharging explosion gases through the outlet (15) out of the main explosion chamber (2).

20. The method according to claim 19, wherein the igniting of the explosion in the main explosion chamber (2) is carried out before the opening of the main explosion chamber and, herein for opening the main explosion chamber, a pressure in the main explosion chamber (2) is measured and the opening of the main explosion chamber (2) is activated as soon as the pressure exceeds a predefined threshold value.

21. The method according to claim 19, wherein the igniting of the explosion in the main explosion chamber (2) is carried out after the opening of the main explosion chamber, and herein the opening of the main explosion chamber (2) is firstly activated, and the explosion in the main explosion chamber is ignited after completion of a predefined ignition delay time.

22. A pressure wave generator (1) with a main explosion chamber (2) and an auxiliary explosion chamber (3), a closure element (9) which in a closure position closes the main explosion chamber (2) with respect to an outlet and in an opening position permits a flow of explosion gases out of the main explosion chamber (2) into the outlet, and an ignition conduit (8) for leading an explosion from the auxiliary explosion chamber (3) into the main explosion chamber (2), characterised in that an ignition conduit valve (7) is arranged in the ignition conduit (8).

23. The pressure wave generator (1) according to claim 22, wherein the ignition conduit valve (7) is an electrically activated valve.

24. The pressure wave generator (1) according to claim 22, wherein the ignition conduit valve (7) is mechanically actuatable by way of a movement of the closure element (9).

25. The pressure wave generator (1) according to claim 22, wherein an element of the ignition conduit valve (7) is formed by a part of the closure element (9) or is fixedly connected to the closure element (9).

26. The pressure wave generator (1) according to claim 25, wherein the closure element (9) comprises an opening or a recess which acts as an ignition conduit (8) or is part of the ignition conduit (8), and the opening is releasable by way of a movement of the closure element (9) from the closure position into the opening position.

27. The pressure wave generator (1) according to claim 22, wherein the closure element (9) can be brought from the closure position into the opening position by way of an explosion in the auxiliary explosion chamber (3).

28. The pressure wave generator (1) according to claim 27, with a spark-generating ignition means, in particular a spark plug (5), for activating the explosion in the auxiliary explosion chamber (3), and a second filling conduit (13) for filling the auxiliary explosion chamber (3), wherein the second filling conduit (13) is not identical to the ignition conduit (8).

29. The pressure wave generator (1) according to claim 27, with an ignition means which can be permanently supplied with energy, in particular a glow plug (5b), for triggering the explosion in the auxiliary explosion chamber (3), wherein the ignition conduit (8) is arranged for filling the auxiliary explosion chamber (3) from the main explosion chamber (2).

30. The pressure wave generator (1) according to claim 22, wherein the closure element (9) can be brought from the closure position into the opening position by way of its own actuator, in particular a pneumatic actuator (4b).

31. A method for operating a pressure wave generator (1) with a main explosion chamber (2) and an auxiliary explosion chamber (3), in particular according to claim 22, comprising the repeated execution of the following steps: filling the main explosion chamber (2) and the auxiliary explosion chamber (3) each with an explosive mixture; igniting an explosion in the auxiliary explosion chamber (3); leading the explosion from the auxiliary explosion chamber (3) through an ignition conduit (8), wherein this leading is interrupted by an ignition conduit valve (7); opening the main explosion chamber (2) with respect to an outlet (15) by way of opening a closure element (9); opening the ignition conduit valve (7) and by way of this leading the explosion into the main explosion chamber (2) and igniting an explosion in the main explosion chamber (2); and discharging explosion gases through the outlet (15) out of the main explosion chamber (2).

32. A method for the operation of a pressure wave generator (1) with a main explosion chamber (2) and with an auxiliary explosion chamber (3), in particular according to claim 22, comprising the repeated execution of the following steps: filling the main explosion chamber (2) with an explosive mixture; moving a closure element (9) in an opening direction; opening an ignition conduit valve (7), in particular by way of moving the closure element (9) and by way of this leading the explosive mixture from the main explosion chamber (2) into the auxiliary explosion chamber (3); igniting an explosion in the auxiliary explosion chamber (3); leading the explosion from the auxiliary explosion chamber (3) through the ignition conduit (8) into the main explosion chamber (2); further moving the closure element (9) in the opening direction for opening the main explosion chamber (2) with respect to an outlet (15) by way of opening a closure element (9), and discharging explosion gases through the outlet (15) out of the main explosion chamber (2).

33. The method according to claim 32, wherein the igniting of the explosion in the auxiliary explosion chamber (3) is effected by way of ignition means which can be constantly supplied with energy, in particular a glow plug (5b).

Description

[0112] The subject-matter of the invention is hereinafter explained in more detail by way of preferred embodiments which are represented in the accompanying drawings. Shown schematically:

[0113] FIG. 1 a longitudinal section through a pressure wave generator;

[0114] FIG. 2 a cross section through the pressure wave generator;

[0115] FIG. 3 a longitudinal section through another embodiment;

[0116] FIG. 4 a section of the longitudinal section for a further embodiment; and

[0117] FIG. 5 a longitudinal section through a further embodiment.

[0118] Basically in the figures, the same parts are provided with the same reference numerals.

[0119] FIGS. 1 and 2 show a pressure wave generator 1 with a main explosion chamber 2 and with an auxiliary explosion chamber 3. A closure element 9 is arranged for closing the main explosion chamber 2 with respect to an outlet 15. The closure element 9 is driven by an explosion in the auxiliary explosion chamber 3, in order to open the main explosion chamber 2 with respect to the outlet 15. A gas spring 4 is arranged for braking this opening movement of the closure element 9. The basic manner of functioning of such a pressure wave generator 1 is explained in the initially cited WO 2007/028264 and WO 2010/025574.

[0120] The closure element 9 is guided on a bearing element 14 which permits a linear opening and closing movement of the closure element 9. The closure element 9 is shaped in a hollow-cylindrical manner and surrounds the bearing element 14 which is fixedly connected to a housing 16. The movement direction, represented by a double arrow, is typically equal to a longitudinal direction of the pressure wave generator 1, and also equal to an outflow direction, in which the explosion gases flow out of the outlet 15. FIG. 1 shows the closure element 9 in a closed position, i.e. the main explosion chamber 2 is closed with respect to the outlet 15.

[0121] The outlet 15 serves for the directed discharge or leading-away of the explosion gases. A pressure wave can be produced herewith.

[0122] A first filling conduit 12 is arranged for filling the main explosion chamber 2 and a second filling conduit 13 for filling the auxiliary explosion chamber 3. The second filling conduit 13 is led through the bearing element 14 to the auxiliary explosion chamber 3. The two filling conduits, as shown, can be commonly fed through a fuel valve 10 or an oxidator valve 11. Alternatively, each of the filling conduits and explosion chambers can be fed by an individual fuel valve or oxidator valve and thus be fed independently of other filling conduit and explosion chamber respectively.

[0123] The two explosion chambers can be filled separately from one another. For example, herein a combustion gas can firstly be filled in at a comparatively low pressure, for example 2 bar, and subsequently an oxidator, for example air, at a high pressure, for example 20 bar.

[0124] A spark plug 5 for igniting the auxiliary explosion chamber 3 is arranged in the bearing element 14. For this, according to the embodiment of FIG. 1, the spark plug 5 is arranged centrally in the region of a symmetry axis (typically in the direction of the longitudinal axis of the device), and can be connected to the auxiliary explosion chamber 3 through a connection opening 6.

[0125] For igniting the explosion in the main explosion chamber 2 with a delay with respect to the explosion in the auxiliary explosion chamber 3, an ignition conduit 8 is present. Two variants of ignition conduits 8 are drawn in FIG. 1, wherein in a realisation of a pressure wave generator 1, as a rule only one is present. [0126] The ignition conduit 8 can be realised as an opening in the closure element 9, said opening being released given the opening movement of the closure element 9.This can be effected by way of an interaction of the closure element 9 with another part of the pressure wave generator 1. Here, this by way of example is the bearing element 14, wherein this with the closure element 9 forms a slider valve 71 as an ignition conduit valve 7: the slider valve 71 opens by way of the closure element 9 being moved along the bearing element 14. [0127] The ignition conduit can be realised as a conduit 8 (represented dashed) with an ignition conduit valve 7 which is arranged thereon. This can be magnet valve 72 or generally an electrically activated valve.

[0128] According to embodiments (not represented) the ignition conduit valve 7 is mechanically actuated given the opening movement of the closure element 9. For this, a mechanical transmission device can be present. This can be adjustable so that the opening of the ignition conduit valve 7depending on the settingtakes place at different positions of the closure element 9. Herein, the opening of the ignition conduit valve 7 can be positively coupled to the opening of the closure element 9, so that the main explosion is only activated when the closure element 9 is already opened.

[0129] By way of the presence of the ignition conduit valve 7, the point in time of the transmission of the explosion from the auxiliary explosion chamber 3 into the main explosion chamber 2 can be controlled.

[0130] FIG. 2 shows a concentric arrangement of the main explosion chamber 2 whichat least in a section which extends in the movement direction of the closure element 9surrounds the auxiliary explosion chamber 3 in the radial direction and is separated from it by the closure element 9.

[0131] The closure element 9 surrounds the bearing element 14, wherein the auxiliary explosion chamber 3 is formed between the closure element 9 and the bearing element 14. On displacing the closure element 9 along the movement direction, the volume of the auxiliary explosion chamber 3 changes. A volume of the gas spring 4 which likewise changes by way of this displacement is formed between the closure element 9 and the housing 16. The gas spring 4 also acts as a block against the propagation of an explosion from the auxiliary explosion chamber 3 into the main explosion chamber 2.

[0132] FIG. 3 shows a pressure wave generator 1 according to another embodiment. The manner of functioning of the elements: main explosion chamber 2, closure element 9, ignition conduit valve 7 or slider valve 71, ignition conduit 8 and outlet 15 is essentially the same as with the embodiment of FIG. 1.

[0133] The auxiliary explosion chamber 3 however is not arranged for driving the closure element 9 but only for generating the auxiliary explosion. The energy of the auxiliary explosion triggers the ignition of the explosion in the main explosion chamber 2 after the release of the slider valve 71 by way of the opening movement of the closure element 9.

[0134] The opening movement of the closure element 9 is effected by way of an active gas spring or pneumatic actuator 4b. This comprises a cylindrical working space 43 with a piston 93 which is moved therein and whose movement is coupled to the movement of the closure element 9, in particular by way of them being fixedly connected to one another, in particular in a single-part manner. In the embodiments of FIGS. 3 and 5, the coupling is effected by way of a piston connection element 94. This is a piston rod in FIG. 3, and a hollow cylinder in FIG. 5.

[0135] The piston 93 divides the working space 43 into a first volume 41 and into a second volume 42. No seal is present between a cylinder inner wall 44 of the working space 43 and the piston 93. In particular, a small gap can also be present, hereinafter called piston gap 96. This permits a gas exchange between the two volumes and herein in particular acts as a throttle. In other embodiments, a separate conduit can be arranged between the first volume 41 and the second volume 42, and can comprise a throttle which permits the gas exchange additionally or alternatively to the piston gap 96. Such a throttle as a piston throttle 10 can also be realised by one or more bores through the piston 93, which likewise permits a gas exchange between the two volumes.

[0136] A gas pressure of the working medium in the first volume 41 effects a force counter to the direction of the opening movement of the closure element 9, wherein a surface [area] which is herein effective is a first piston surface 91.

[0137] A gas pressure of the working medium in the second volume 42 effects a force in the direction of the opening movement of the closure element 9, wherein a surface area which is herein effective is a second piston surface 92.

[0138] Herein, the second piston surface 92 is smaller than the first piston surface 91 for example at least five or ten or twenty percent smaller.

[0139] The piston 93 comprises a piston closure element 95 which in the course of the opening movement closes a cylinder inlet/outlet 45 or inlet/outlet opening of the first volume 41. The cylinder inlet/outlet 45 here is drawn concentrically to the working space 43, but alternatively could also be arranged laterally.

[0140] A braking or an end-position damping of the opening movement is effected by way of the closing of the cylinder inlet/outlet. At the same time, the pressurised air valve 49 is also protected from a pressure impact through the pressurised air filling conduit 48.

[0141] The cylinder inlet/outlet 45 can be opened by a cylinder discharge valve 46. The working medium flows for example through a discharge or vent conduit 102. The cylinder discharge valve 46 can have a relatively large valve cross section, compared to a filling conduit. Herewith, an abrupt pressure reduction in the first volume 41 can be realised. The cylinder discharge valve 46 is held closed by a pressure in a pressurised air filling conduit 48. This pressure can be reduced by way of opening the discharge pilot valve 47. The opening movement of the closure element is therefore activated by the opening of the discharge pilot valve.

[0142] The cylinder discharge valve 46 by way of example is a seat valve with a movable shut-off body. The shut-off body comprises a piston surface 52, on which it is impinged by the pressurised air from the pressurised air filling conduit 48 in a discharge valve volume 51. A valve surface 53 which is subjected to the pressure in the cylinder inlet/outlet 45 is smaller than the piston surface 52. The forces upon the piston surface 52 and the valve surface 53 are opposite to one another. If the discharge pilot valve 47 is closed, then the gas pressure at the two surfaces is the same, and the force upon the piston surface 52 is greater than that upon the valve surface 53, by which means the shut-off body or the cylinder discharge valve 46 is held in the closed position.

[0143] The pressurised air filling conduit 48, via a section 101 of the pressurised air filling conduit 48 also feeds the first volume 41. The pressurised air filling conduit 48 in turn is fed via a pressurised air valve 49.

[0144] A venting conduit 97 effects a pressure compensation between the ambient air and an intermediate cylinder. The intermediate cylinder lies between a rear end of the closure element 9 and the active gas spring or the pneumatic actuator 4b.

[0145] In the variant of the embodiment of FIG. 3, the working space 43 and the piston 93 are realised in a compact manner. The same manner of functioning however can also be realised with separate first and second volumes and with separate pistons with different piston surface areas. Herein, a conduit with a throttle is arranged between the two volumes and the movements of the two pistons are mechanically coupled. This means that a linear movement of one of the two pistons always also causes a linear movement of the other piston.

[0146] In the embodiments of FIG. 3 and also of the other figures, a piston path can be for example between 20 mm and 150 mm, in particular between 30 mm and 80 mm. A diameter of the piston can be for example between 20 mm and 200 mm, in particular between 40 mm and 120 mm.

[0147] FIG. 3 shows the pneumatic actuator 4b in combination with a pressure wave generator 1. The pneumatic actuator 4b however can also be used in other applications. For this, the piston rod 94 can be coupled to another element, or the movement of the piston rod can be coupled to the movement of another element.

[0148] FIG. 4 shows a detail of a pressure wave generator 1 according to another embodiment, a variant of the embodiment of FIG. 3. The manner of functioning of the elements: main explosion chamber 2, closure element 9, ignition conduit valve 7 or slider valve 71, ignition conduit 8, outlet 15 and of the pneumatic actuator 4b is essentially the same as with the embodiment of FIG. 3.

[0149] In this variant, the auxiliary explosion chamber 3 has no individual filling conduit 13. It is designed in a comparatively small manner. Instead of a spark plug 5, it comprises a glow plug. On operation of the pressure wave generator 1, this is not only supplied at an ignition point in time, but can be supplied in a constant manner, i.e. it can glow permanently or over a longer time, e.g. several seconds or minutes. Herewith, it can have a high temperature, and herewith again can introduce sufficient energy into the gas mixture, in order to trigger a rapidly propagating explosion or detonation in the main explosion chamber 2. Depending on the gas mixture and pressure, this would not be possible with a spark plug, but it would firstly only activate a combustion which only after a certain time (for example 30-50 ms) leads to an explosion. The ignition in the main explosion chamber 2 is effected by way of the glow plug being supplied with energy after the filling of the main explosion chamber 2 and being brought up to its operating temperature. This can last a few seconds, for example five or ten seconds. If then the slider valve 71 releases the ignition conduit 8 by way of the opening movement of the closure element 9, the explosive gas mixture flows from the main explosion chamber 2 into the auxiliary explosion chamber 3 and comes into contact with the heated glow plug. This triggers the explosion in the auxiliary explosion chamber 3 and through the ignition conduit 8 also in the main explosion chamber 2. The opening movement of the closure element 9 is effected by way of the pneumatic actuator 4b as has already been described above.

[0150] On operation of this variant, the following methods steps can be carried out: [0151] Opening the pressurised air valve 49 given a closed discharge pilot valve 47. This has the following effects: the pressure in the pressurised air filling conduit 48 (e.g. 70 bar) closes the cylinder discharge valve 46. The first volume 41 is subjected to or impinged by pressurised air through the pressurised air filling conduit 48. The second volume 42 is also subjected through the piston gap 96, wherein with time the same pressure is present in both volumes. Since the first piston surface 91 is larger than the second piston surface 92, the piston 93 and hence the closure element 9 is moved into a closed position (counter to the direction of the opening movement). [0152] Closing the pressurised air valve 49. The closure element 9 remains in the closed position. [0153] Opening the fuel valve 10 and the oxidator valve 11 and by way of this filling the main explosion chamber 2 and, depending on the embodiment, also the auxiliary explosion chamber 3. Herein, the fuel valve 10 can firstly be opened given a closed oxidator valve 11, and a controlled quantity of fuel can be introduced at a first pressure. Then, given a closed fuel valve 10, the oxidator valve 11 can be opened and a quantity of oxidator can be introduced up to a higher second pressure. The quantity share of oxidator and fuel can be adjusted by way of the ratio of the first and second pressure. Typically, the quantity share is selected as a stoichiometric ratio in accordance with the chemical reaction on combustion or explosion. For example, propane can be used as fuel and air as an oxidator, in a quantity ratio or pressure ratio of 1:15 to 1:24. [0154] One of the following two method variants (more concerning this further below): [0155] Either: triggering the auxiliary explosion in the auxiliary explosion chamber 3 by way of activating the spark plug 5, subsequent activating the opening movement and, by way of opening the ignition conduit valve 7, triggering the explosion in the main explosion chamber 2. [0156] Or: activating the opening movement and by way of this subsequent triggering of the explosion in the main explosion chamber 2 by way of combustion gas getting through the ignition conduit valve 7 to the glow plug. [0157] In both cases, the activating of the opening movement is effected by way of opening the cylinder discharge valve 46, which in particular can be effected by way of opening the discharge pilot valve 47 and the reduction of the pressure in the pressurised air filling conduit 48. The pressure in the first volume 41 drops by way of the opening of the cylinder discharge valve 46. The pressure in the second volume 42 likewise drops, but on account of the throttle effect of the piston gap 96 drops more slowly than in the first volume 41. By way of this, in turn the force upon the second piston surface 82 is larger than the force upon the first piston surface 91. This effects a movement of the piston 93 and thus the opening movement of the closure element 9. [0158] Before the piston 93 or the closure element 9 hit a stop, the piston closure element 95 closes the cylinder inlet/outlet 45. The air which remains in the (now smaller) first volume 41 is compressed and brakes the movement of the piston 93 and of the closure element 9. One prevents the pressurised air valve 49 from being loaded by a pressure peak. [0159] The explosion gases flow out of the opening which has been released by the closure element 9. [0160] Closing the cylinder discharge valve 46, in particular by way of closing the discharge pilot valve 47. This can be effected by way of a piston surface, via which the pressurised air in the pressurised air filling conduit 48 presses the cylinder discharge valve 46 or its shut-off body into the closed position, being larger than a surface, on which the pressurised air acts in the opposite direction upon the cylinder discharge valve 46 or its shut-off body. After the closing of the cylinder shut-off valve 46, the pressure in the first volume 41 can still be adequately high (e.g. 20 bar), in order to also move back the piston 93 after a pressure compensation with the second volume 42 and to herewith bring the closure element 9 into the closed position. [0161] Subsequently, the method can be begun again with the opening of the pressurised air valve 49.

[0162] The aforedescribed method variants are variants of the device with a spark plug or glow plug. The differences lie in the fact that [0163] in the variant with the spark plug, the ignition in the auxiliary explosion chamber 3 is effected before the activating of the opening movement, e.g. 50 ms beforehand. In this time, an explosion with sufficient energy has developed in the auxiliary explosion chamber 3, in order in the course of the opening of the ignition conduit valve 7 or slider valve 71 by way of the opening movement to trigger the necessary rapid explosion in the main explosion chamber 2. [0164] In the variant with the glow plug, this can already bring in sufficient energy for the rapid explosion in the main explosion chamber 2, if on opening the ignition conduit valve 7 or slider valve 71 the gas mixture flows to the glow plug.

[0165] In both variants, thanks to the introduced ignition energy, it only lasts e.g. about two ms until the explosion has propagated in the main explosion chamber 2. An explosion pressure builds up in the main explosion chamber 2 whilst the opening movement already takes place. A maximal energy in the gas flow arises in the outlet 15 when the explosion pressure is maximal at the point in time when the opening of the closure element 9 between the main explosion chamber 2 and the outlet 15 is also maximal.

[0166] In other embodiments, the spark plug 5 or the glow plug 5b is arranged for igniting gas mixture or for triggering the explosion in the main explosion chamber 2. In these embodiments, in particular there is no auxiliary explosion chamber 3 and no ignition conduit 8. The igniting of the explosion in the main explosion chamber 2 is synchronised with the moving of the closure element in the opening direction by way of a control 20. Herein, depending on the speed at which the explosion propagates in the main explosion chamber 2 and at which the pressure in the main explosion chamber 2 builds up, the movement of the closure element 9 can be effected before or after the ignition in the main explosion chamber 2.

[0167] For example, the explosion in the main explosion chamber 2 can propagate relatively slowly. The opening under certain circumstances can then be effected not until after the ignition. In detail, herein the exemplary following steps are repeatedly carried out for operating the pressure wave generator (1) with a main explosion chamber (2): [0168] filling the main explosion chamber (2) with an explosive mixture; [0169] igniting an explosion in the main explosion chamber (2); [0170] measuring a pressure in the main explosion chamber (2) and, as soon as a the pressure exceeds a predefined threshold value, activating an opening of the main explosion chamber (2), in particular by way of a pneumatic actuator, in particular the pneumatic actuator (4b) which is described here; [0171] moving, by way of the pneumatic actuator (4b), a closure element (9) in an opening direction for opening the main explosion chamber (2) with respect to an outlet (15), and discharging explosion gases through the outlet (15) out of the main explosion chamber (2); [0172] closing the main explosion chamber (2) by way of moving the closure element (9) in a closure direction by way of the pneumatic actuator (4b).

[0173] Alternatively, if the explosion propagates comparatively rapidly in the main explosion chamber 2, under certain circumstances the opening can already be activated before the ignition. In detail, the exemplary following steps are herein repeatedly carried out for operating the pressure wave generator (1) with a main explosion chamber (2): [0174] filling the main explosion chamber (2) with an explosive mixture; [0175] moving a closure element (9) in an opening direction, in particular by way of a pneumatic actuator, in particular the pneumatic actuator (4b) which is described here; [0176] igniting, after completion of a predefined ignition delay time, an explosion in the main explosion chamber (2); [0177] further moving the closure element (9) in the opening direction for opening the main explosion chamber (2) with respect to an outlet (15), and discharging explosion gases through the outlet (15) out of the main explosion chamber (2); [0178] closing the main explosion chamber (2) by way of moving the closure element (9) in a closure direction by way of the pneumatic actuator (4b).

[0179] As to whether the explosion propagates comparatively slowly or quickly, amongst other things depends on the applied explosive (gas) mixture, its pressure and temperature and on the applied ignition means glow (plug or spark plug), etc.

[0180] On using the pneumatic actuator 4b, as described above, the moving of the closure element in the opening direction is effected by the movement of the pneumatic actuator in the second direction. The moving of the closure element in the closure direction is effected by way of the movement of the pneumatic actuator in the first direction.

[0181] FIG. 5 shows an embodiment with only one main explosion chamber 2, thus without an auxiliary explosion chamber 3 and without an ignition conduit 8. FIG. 5 also shows an alternative pneumatic actuator 4b which is different to that of FIG. 3. The complete pneumatic actuator which is shown in FIG. 5 or also only individual elements, for example [0182] a piston throttle 100 and/or [0183] a closure element 9 with a hollow cylinder instead of the piston rod as a piston connection element 94 and/or [0184] a cylinder discharge valve 46 with a section 101 of the pressurised air filling conduit can be combined with a pressure wave generator 1 with an auxiliary explosion chamber 3 such as for example according to FIG. 3.

[0185] The manner of functioning is basically the same as that of the embodiment of FIG. 3, with the following differences in the realisation of the individual elements:

[0186] The piston connection element 94 which connects the piston 93 to the closure element 9 is formed by a hollow cylinder. The piston 93 encompasses a rear closure guide 98 which can be designed as a general cylinder, in particular as a circular cylinder and is linearly movable along this in the movement direction. The piston connection element 94 surrounds the bearing element 14 which is fixedly connected to a housing 16. The second volume 42 lies between the rear closure guide, the piston 93 and the inner side of the hollow cylinder or of the piston connection element 94.

[0187] The throttle between the first volume 41 and the second volume 42 is realised as a piston throttle 100 by one or more bores through the piston 93. Additionally or alternatively however, the function of the piston throttle can also be assumed by a gap between the piston 93 and the rear closure guide 98.

[0188] The section 101 of the pressurised air filling conduit 48, through which the first volume 41 is supplied with the working medium does not run through the housing 16 but through the shut-off body of the cylinder discharge valve 46, for example as a bore, and can also be called a piston throttle of the cylinder discharge valve 46. Hence the first volume 41 is supplied with the working medium via the discharge valve volume 51.

[0189] One can make do without an end-position damping. If in the embodiment of FIG. 5 an end-position damping is to be realised, then this can be effected as in FIG. 3 by way of a projecting closure element 95 which moves into the cylinder inlet/outlet 45, or by way of the cylinder inlet/outlet 45 being led laterally into the first volume 41, and being closed by way of the piston 93 sliding over the cylinder inlet/outlet 45 given the opening movement.